JSON Formatter & Validator
Format, validate or minify JSON in your browser, locate syntax errors, and copy or download clean JSON without sending pasted data to WebToolMint.
What this tool solves
Format, minify and validate JSON, locate syntax errors, copy or download the result, with input processed locally in the browser.
Input: JSON text, from a copied API response, configuration file or sample payload.
Output: formatted or minified JSON plus validation success or a syntax error message.
How to use it
- Paste a complete JSON value, choose 2 spaces, 4 spaces or tabs, then select Format. Use Minify to remove formatting whitespace.
- Output preserves number literals, including large integers and long decimals. An ID such as 9007199254740993 remains unchanged.
- Use the reported error location to check quotes, trailing commas or comments. Editing the input clears the old result; format or minify again before copying or downloading.
Common use cases
- Debug API responses and configuration files
- Beautify compact JSON for code review
- Minify valid JSON for tests or transfer
Privacy, accuracy and limits
JSON does not allow comments, single-quoted strings or trailing commas. Extremely large payloads can make the browser editor slow.
WebToolMint keeps this workflow local in the browser where the feature allows it. Network-dependent tools are labelled separately. Keep originals and independently verify results that affect legal, financial, medical or business decisions.
Frequently asked questions
Can a formatter repair invalid JSON automatically?
A formatter can identify syntax errors, but silently guessing repairs can change data. Fix the reported issue deliberately.
Why is my JavaScript object not valid JSON?
JavaScript object literals can use syntax that JSON forbids, such as comments, undefined values or single-quoted strings.
Is pasted JSON uploaded?
The formatter is designed to process the input in the browser, which is useful for ordinary local inspection. Always follow your organization’s rules for sensitive data.
Related tools
Related guides
Worked example and limits
Format {"id":9007199254740993,"active":true} and compare every ID digit with the input. The value true must remain a boolean. Then try {"a":1,}: this must report invalid JSON rather than guess a repair. Formatting whitespace does not verify the meaning of a field or whether an API accepts it.